Judgment of PCB circuit board good or bad way:
First: from the appearance of the circuit board to distinguish between 
good and bad
Under normal circumstances, PCB circuit board appearance can be judged 
by three aspects;

1, the size and thickness of the standard rules.

The thickness of the circuit board to the standard circuit board is 
different depending on the size of the product and can be measured 
according to the thickness and specifications of the product.

2, light and color.

External circuit boards are covered with ink, the circuit board can play 
the role of insulation, if the color of the board is not bright, less 
ink, insulation board itself is not good.

3, the appearance of the weld.

Circuit board due to more parts, if the welding is not good, parts easy 
to fall off the circuit board, seriously affect the quality of the 
circuit board welding, the appearance of good, carefully identified, the 
interface is very important point is very important.
Second: high-quality PCB circuit board needs to meet the following 
requirements
1, requiring components installed after the phone to be easy to use, 
that is, to meet the requirements of electrical connections;
2, the line width, line thickness, line spacing meet the requirements, 
so as to avoid the line heat, open circuit, and short circuit;
3, by the high temperature copper is not easy to fall off;
4, copper surface is not easy to oxidation, affecting the installation 
speed, after oxidation soon after the bad;
5, no additional electromagnetic radiation;
6, the shape is not deformed, so as not to install after the shell 
deformation, screw hole dislocation. Are now mechanized installation, 
circuit board holes and lines and design of the deformation error should 
be within the allowable range;
7, and high temperature, high humidity and resistance to special 
circumstances should also be considered within the scope;
8, the surface of the mechanical properties to meet the installation 
requirements.